One structure for a semiconductor diode, such as a Schottky rectifier, includes a semiconductor layer onto which two metal contacts, including an ohmic contact and a Schottky contact, are formed. In high-power applications, these diodes must be able to withstand relatively large reverse-bias voltages without breaking down, i.e., without conducting current in the reverse direction. One factor that influences the reverse breakdown voltage is the width of the depletion region in the semiconductor layer. In general, a wider depletion region, and thus a wider diode, has a higher reverse breakdown voltage.
The doping level of the diode's semiconductor layer also influences its reverse breakdown voltage. In general, a lower doping level leads to a wider depletion region, which, in theory, leads to better performance in high power applications. However, reducing the doping level also increases the diode's on-state resistance, i.e., the resistance of the diode when conducting in the forward-bias mode. Greater on-state resistance leads to increased voltage drop across the diode, which limits the diode's utility and efficiency in many applications. As a result, reductions in doping level and corresponding gains in reverse breakdown voltage are limited by the acceptable on-state resistance of the diode.